The gate of the closed Smithsonian's National Zoo is seen, Jan. 2, 2019, in Washington.
The gate of the closed Smithsonian's National Zoo is seen, Jan. 2, 2019, in Washington.

A shutdown of about a quarter of the U.S. government rolled into its 12th day on Wednesday, with lawmakers and President Donald Trump divided over his demand for money for a border wall. 
The shutdown, which began Dec. 22, is the 19th to occur since the mid-1970s. Most have been brief. Trump's latest is the third on the Republican president's watch and already ranks among the longest ever. 
There were several very short shutdowns under Republican President Ronald Reagan. Under Democratic President Bill Clinton, there were two shutdowns, including the longest on record: 21 days in 1996. 
A 16-day shutdown happened under Democratic President Barack Obama in 2013 in a fight with Republicans over his health care law. 
The current shutdown has not affected three-quarters of the government, including the Department of Defense and the Postal Service, which have secure funding. But 800,000 employees from the departments of Homeland Security and Transportation and other agencies have been furloughed or are working without pay. 
Here is what is happening around the federal government: 
The Smithsonian museums and the National Zoo in Washington are closed because of the shutdown, according to the Smithsonian website. Among these is the popular National Museum of African American History and Culture, which opened in 2016. "The museum is closed due to the federal government shutdown. Timed entry pass holders will be emailed instructions on how to reschedule their visit," the museum posted on Instagram.

FILE - Pedestrians cross into Juarez, Mexico, as U
FILE - Pedestrians cross into Juarez, Mexico, as U.S. Customs and Border Protection officers patrol the Paso del Norte Port of Entry in El Paso, Texas, Feb. 16, 2016.

?Homeland Security 
The department that oversees Customs and Border Protection, Immigration and Customs Enforcement, the Transportation Security Administration, the Coast Guard and the Secret Service is affected. But most employees are "essential," so they are working without pay until a funding bill is passed. 
Of 245,000 agency employees, nearly 213,000 have been deemed "essential," according to the department's contingency plan. 
Housing and Urban Development 
Most of this department's 7,500 employees are "non-essential"; only about 340 are working. Nearly 1,000 others may be called in for specific tasks, without pay. 
Public housing authorities and Native American tribal housing entities are not part of the federal government and so are not required to shut down. But the federal government provides some of their funding, so they may need to reduce or change operating hours.  

FILE - Jennifer Gomez talks with U.S. Rep. Adriano
FILE - Jennifer Gomez talks with U.S. Rep. Adriano Espaillat about repairs needed in her apartment in public housing in New York, July 3, 2018.

HUD, which oversees some housing loan and low-income housing payment programs, warned in its contingency plan that "a protracted shutdown could see a decline in home sales, reversing the trend toward a strengthening market that we've been experiencing." 
The Department of Commerce's Bureau of Economic Analysis and Census Bureau are not publishing economic data, including key figures on gross domestic product, inflation, personal income, spending, trade and new home sales, during the shutdown. 
Office of Personnel Management 
The agency that oversees the federal workforce has given advice to workers on dealing with landlords, mortgage lenders and other creditors, including sample letters explaining lost income because of the lack of federal funding. 

Federal Communications Commission

The FCC, which regulates radio and television broadcast and cable systems, said it would suspend most operations at midday on Thursday if the shutdown was still in effect. Work for "the protection of life and property" will continue. So will operations at the agency's Office of Inspector General, the FCC's internal watchdog. 
Coast Guard 
Members of the Coast Guard were due to get their final 2018 paychecks on Monday, their last until the government reopens. 
The Federal Emergency Management Agency was to resume issuing new flood insurance policies during the shutdown, reversing an earlier decision. 

A man runs past a National Park Service sign in Sa
FILE - A man runs past a National Park Service sign in San Francisco, Dec. 22, 2018. A partial federal shutdown has been put in motion because of gridlock in Congress over funding for President Donald Trump's Mexican border wall.

The National Park Service, under the umbrella of the Interior Department, is operating with a skeleton staff. Under its contingency plan, some parks may be accessible, with others closed completely. The National Park Service is providing no visitor services such as restrooms, facility and road maintenance, and trash collection. 

Of its 55,000 employees, 20,400 have been put on leave. This excludes most of the Federal Aviation Administration, where 24,200 are working, and the Federal Highway Administration, where all 2,700 employees are funded through other sources. 
Air traffic control, hazardous material safety inspections and accident investigations continue, but some rulemaking, inspections and audits have been paused. 
Executive Office of the President 
An estimated 1,100 of the office's 1,800 employees are on leave. This includes most of the Office of Management and Budget, which helps implement budget and policy goals.